Cytotoxic T-lymphocyte cells play a central role in the biological defense against what are commonly considered irreversible, pathogenic infections with human immunodeficiency virus (HIV). It is believed that, as a consequence of HIV infection, cytotoxic T-lymphocyte cells are recruited to limit the spread of viral infection by recognizing and lysing viral-infected cells. A central role in the expression of anti-viral activity of cytotoxic T-lymphocyte cells is played by a cell surface molecular receptor signaling process whereby cell surface sensing proteins detect the presence of HIV peptides contained in the viral envelope or viral-specific enzymes.
In HIV-infected individuals who have not developed AIDS opportunistic infections, there is a high frequency of circulating T cells bearing T cell receptors that recognize HIV-infected cells. Despite the vigorous expansion of antiviral T cells which can develop into cytotoxic effector cells capable of lysing HIV-infected targets and which secrete soluble factors capable of suppressing HIV replication, the cellular immune response eventually becomes unable to control viral production, the HIV-infected individual having become deficient in immunocompetence.